Vote for change: the teenagers hoping to get to No 10. Photograph: Jamie Baker for the Observer

Over the next few weeks, many of the youngsters standing in front of me will be bunking off school. But rather than head off to a music festival, or even a riot, these teenagers will be heading to the political party conferences. Some of those about to start university are even contemplating missing freshers' week. Instead of sleeping in, they'll be getting up early in the hopes of running into David Cameron, Ed Miliband or Nick Clegg, and they'll be hoping to make an impression.

These leading lights of the three main political parties' youth wings – Conservative Future, Liberal Youth and Young Labour – explode the idea that teenagers are selfish and self-absorbed. The group, ranging in age from 12 to 19, may still have the hollowed postures and self-conscious glances of their age (one Lib Dem hides behind a fringe that stretches halfway down his face), but they're passionate about social justice and have more than a grasp of economics. These are, we're told by the parties, Westminster's future stars, and one day some of them will run the country.

The kids are keen to emphasise the words "one day". David Cameron may be the youngest prime minister in Britain for 200 years, but there is apparently nothing cool about being a "career politician". "You've got to be able to bring some life experience to politics," one of them says.

Many were brought up in political households. Maelo Manning, whose mother is a senior policy offer in Vince Cable's department for business, innovation and skills, attended conference at age eight – drinking banana milkshakes in the creche by day and attending fringe events in the evenings. In Birmingham this month Maelo, now 12, will deliver her fourth speech. But not all have followed in their parents' footsteps. While some have never considered supporting another party, others have rebelled and crossed sides; some say their parents won't share their political leanings so as not to influence them. Others have parents who couldn't be less interested: "My mum has a sleep in the chair when Newsnight comes on," says one.

From very different backgrounds, these young people have done something deeply unfashionable: join a political party. You'd expect they'd all be behind the lowering of the voting age to 16 – they're not – but they are resolute that youth should have a voice in politics. As William Hague pointed out when addressing the Tory Party conference at 16: "Half of you won't be here in 30 or 40 years' time." Their sentiments exactly. "Listen to us," says Claire Boad, age 12, "and you might learn something."

CONSERVATIVE FUTURE: "We love Lady gaga"

They're a stiff bunch, the Tories, and you can see it in their poses for the camera – heaven forbid if arms are touching! They pride themselves on being the "grown-up" youth wing that takes politics "most seriously". But snooty? They disagree.

"I think the younger Conservatives are much less reserved than in the past," says 18-year-old Holly Carter, chair of Essex, the land of reality show TOWIE (she won't be drawn on the concept of vajazzling). And they're not posh? "We're waiting for the jokes about keeping horses and wearing tweed," they sigh collectively.

Although others hail from rural Tory heartlands such as Berkshire, Sussex, Kent and Surrey, just one of them has been educated privately, with the rest attending state schools. "It's actually not the case, the old Etonian thing," pipes up 17-year-old Sadie Vidal, deputy chair of Wales, who professes a love of Lady Gaga and Jimmy Carr (other interests among the group include hockey, scuba diving and, um, sailing).

Dakota Dibben, a 19-year-old student and scout leader who runs his own model-railway business, is probably the closest you get to egg-headed, but then there is Oliver Sanderson, an army forces kid with a Leeds accent, who got into politics when Margaret Thatcher visited his school in 2009 and gave a speech. "My dad's in the army, so he's not allowed to be interested," he says, adding he'd like to be an MP for Harrogate.

What do they think of they way Cameron is leading the country? They all nod at me. "It's difficult being in coalition," says Connor Relleen, 19, "but he's brought us more to the centre ground and we're more diverse than they've ever been." "We're the party of aspiration," says Holly.

I wonder what they made of the behaviour of other, less politically enfranchised teens during the riots. What were their own experiences? "We were on holiday" is a common response.

LIBERAL YOUTH: "We're definitely the weirdest party"

The party for the politically precocious, Liberal Youth is the only organisation that doesn't operate a minimum age for membership (Young Labour and Conservative Future are for over-15s). The 12-year-old Claire Boad, who would like to juggle a modelling career with becoming the first female Lib Dem prime minister, is by no means the youngest. Her father – wearing a coalition badge that says: "We may be together, but we're in separate beds" – tells me that her younger brother Simon, eight, could teach me a thing or two about politics.

Maelo Manning, also 12, and wearing trainers with the slogan "I ❤ cupcakes", describes herself as a "child feminist" and has 120,000 followers at Libdemchild.com. She wants to study PPE at university, followed by a masters, then a career in ethical investment banking. "But I might drop economics," she tells me matter-of-factly.

The other parties goad them about their open-door policy ("It's really scraping the barrel getting the 12-year-olds in!"), but the Lib Dems banter back. "We're definitely the weirdest party," laughs 15-year-old Matt Downey from Cambridge – he of the elongated fringe – "and you get a lot of outcasts, a lot of different, mad opinions. We have a laugh with it." Noticeably this is the only group that isn't entirely white.

Liberal Youth has managed to pilfer from Labour and the Tories. Amanda Garoes-Hill, a 19-year-old raised in Bradford in a lone-parent family, ditched Labour after it abolished the 10p tax rate: "It made me realise they did not represent the disadvantaged." Then there's Harry Matthews, a crisp-shirted university student who aced his Eton entrance interview after he gave a speech in praise of Iain Duncan Smith. In 2010, after watching Nick Clegg's live pre-election appeal on TV, he had an "identity crisis" and switched parties: "I was shocked. I just thought: 'I agree with a lot of this.'"

The other kids call them fickle. "Oh, new, shiny Nick Clegg!" they tease, sounding like characters from The Inbetweeners. "It's the new party that hasn't been in power for 70 years!"

How do they feel now that their leader's golden hour is over? "We were caught between a rock and hard place when the coalition was elected, and whatever we had done would have been wrong," says Harry, shrugging.

YOUNG LABOUR "I was so keen to join I stayed up until midnight"

he Brit School of performing arts in Croydon (attended by Adele, Jessie J and Leona Lewis) doesn't seem an obvious breeding ground for a future politician. But Jack Slater, 16, says you'd be surprised. "When I first got there I wasn't all that interested in politics," says Slater, who'd like to make pop videos before governing Britain. "But we had classes that give you a good grasp of it. They encouraged me to join a party."

Jack spends most Saturdays campaigning on street stalls in his home neighbourhood of Brixton, south London, and like many in Young Labour, he's passionate about introducing a formal political education.

Several in the group have had personal experience of the welfare system after fathers left home or houses were repossessed. Billy McCauley, a 16-year-old from Glasgow, has supported Labour since he was 14, when he and his mother became homeless; they still live in temporary accommodation. But there are plenty of children from wealthy families here, too. "There's definitely more of a mix of people in the party post-Blair," says Joe Collin, who has set up the first Young Labour group in the Tory-dominated constituency of Sutton Coldfield. The 18-year-old eschews leafleting, preferring to campaign by putting on music gigs.

Like his leader Ed Miliband before him, Collin has a place at Oxford university. How does he feel about crippling fees? "The betrayal of Nick Clegg is one thing, but he's trebled fees, not just raised them," says Joe. "A lot of my friends think Clegg's weak and pointless," adds Rory Weal, 16. "Well, he is." The Big Society, adds Joe, is "Thatcherism with a smile".

There's plenty of bite to the Young Labour rhetoric, accompanied by a slightly geeky enthusiasm: becoming a member is a moment, like passing their driving tests and getting exam results, that the majority of the group talk about giddily. McCauley was so keen to join that he "stayed up until midnight on my 15th birthday and did it online". Emma Maton, 15 and responsible for recruiting more girls into Kent Young Labour, confesses she tried to apply several times when she was underage, but couldn't get past the system. With eager recruits like these, you wonder what the need is for campaigning. "We don't need to do so much work to recruit people any more," grins Joe. "Not since the 2010 election."

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